refactor(app): App-per-screen navigation, remove menu_level entirely

Splits the ad-hoc menu_level state machine into standalone Apps with a
uniform parent/child exit convention (long-press CONFIRM -> parent):
clock_app renamed to home_app (boot-default), new set_clock_app
extracted from home_app's time-edit mode, new ipc_bind_app extracted
from menu_app's old level-2 screen, and the sensor-type selection step
merged into pair_app as its new initial state. menu_app now only holds
the 4-item top-level list (language toggle inline). Also makes both
menu_app and pair_app's up/down navigation cyclic (wraps at both ends).

App/app_home.c

@@ -0,0 +1,103 @@
+#include "app_manager.h"
+#include "clock.h"
+#include "xtell.h"
+#include "ui.h"
+#include "rgb.h"
+#include "event.h"
+#include "system.h"
+#include "../Drivers/rf.h"
+#include "../Drivers/lcd.h"
+#include "../Drivers/pcf8563.h"
+
+// 外部引用的全局系统状态变量
+extern SystemState current_state;
+extern volatile u16 ms_tick;
+
+// 声明本应用的生命周期回调函数
+static void HomeApp_OnStart(void);
+static void HomeApp_onRun(void);
+static void HomeApp_onClose(void);
+static EventResult HomeApp_onEvent(SystemEvent *evt);
+
+// 实体化定义待机时钟主页应用控制块 (开机默认显示的首屏)
+WristbandApp home_app = {
+    APP_ID_HOME,
+    "Home",
+    HomeApp_OnStart,
+    HomeApp_onRun,
+    HomeApp_onClose,
+    HomeApp_onEvent
+};
+
+/**
+ * @brief HomeApp 启动回调
+ */
+static void HomeApp_OnStart(void)
+{
+    current_state = STATE_NORMAL;   // 系统切入正常待机状态
+    RF_SetMode(1);                  // 开启天线并置为接收模式，监听无线探测器
+
+    // 尝试从 PCF8563 RTC 芯片中读取硬件时间 (具备非阻塞防卡死保护)
+    if (PCF8563_Init()) {
+        PCF8563_ReadTime(&current_hour, &current_min, &current_sec);
+        XTELL_LOG("[HomeApp] RTC Hardware Synced OK!\r\n");
+    } else {
+        XTELL_LOG("[HomeApp] RTC Hardware Offline, using system clock.\r\n");
+    }
+
+    // 绘制并渲染待机时钟主页面画面
+    UI_ShowClockPage(current_state, current_hour, current_min);
+
+    // 关断/熄灭 FCOB 双灯条
+    RGB_Send(0, 0, 0, 0, 0, 0);
+
+    XTELL_LOG("[HomeApp] Started\r\n");
+}
+
+/**
+ * @brief HomeApp 轮询主回调
+ */
+static void HomeApp_onRun(void)
+{
+    // 软时钟发生分钟改变，需要通知屏幕重画时钟主页
+    if (clock_updated) {
+        clock_updated = 0;
+        UI_ShowClockPage(current_state, current_hour, current_min);
+    }
+}
+
+/**
+ * @brief HomeApp 退出清理回调
+ */
+static void HomeApp_onClose(void)
+{
+    RGB_Send(0, 0, 0, 0, 0, 0); // 关闭灯条
+    XTELL_LOG("[HomeApp] Closed\r\n");
+}
+
+/**
+ * @brief HomeApp 接收事件处理回调 (按键导航与布撤防交互)
+ */
+static EventResult HomeApp_onEvent(SystemEvent *evt)
+{
+    // 1. 长按 ■ 确认键，打开设置主菜单 MenuApp
+    if (evt->key_event == KEY_EVENT_CONFIRM_LONG) {
+        AppManager_SwitchToForeground(&menu_app);
+        return EVENT_HANDLED;
+    }
+
+    // 2. 长按 ▲ 键，一键切换系统的 布防 (ARMED) 和 撤防 (DISARMED) 状态
+    if (evt->key_event == KEY_EVENT_UP_LONG) {
+        if (current_state == STATE_ARMED) {
+            current_state = STATE_DISARMED;
+        } else {
+            current_state = STATE_ARMED;
+        }
+        // 布撤防状态切换成功后进行 100ms 短震确认，并重新刷写时钟待机页
+        MOTOR = 1; Delay_ms(100); MOTOR = 0;
+        UI_ShowClockPage(current_state, current_hour, current_min);
+        return EVENT_HANDLED;
+    }
+
+    return EVENT_IGNORED; // 其他未被关心的事件交由后台应用或丢弃
+}